48
4-3-4
OUTPUT and OUTPUT NOT
The simplest way to output the results of combining execution conditions is to
output it directly with the OUTPUT and OUTPUT NOT. These instructions are
used to control the status of the designated operand bit according to the ex-
ecution condition. With the OUTPUT instruction, the operand bit will be
turned ON as long as the execution condition is ON and will be turned OFF
as long as the execution condition is OFF. With the OUTPUT NOT instruc-
tion, the operand bit will be turned ON as long as the execution condition is
OFF and turned OFF as long as the execution condition is ON. These appear
as shown below. In mnemonic code, each of these instructions requires one
line.
00000
00201
00200
00001
Address
Instruction
Operands
00000
LD
00000
00001
OUT
00200
Address
Instruction
Operands
00000
LD
00001
00001
OUT NOT
00201
In the above examples, IR 00200 will be ON as long as IR 00000 is ON and
IR 00201 will be OFF as long as IR 00001 is ON. Here, IR 00000 and IR
00001 would be input bits and IR 00200 and IR 00201 output bits assigned to
the Units controlled by the PC, i.e., the signals coming in through the input
points assigned IR 00000 and IR 00001 are controlling the output points as-
signed IR 00200 and IR 00201, respectively.
The length of time that a bit is ON or OFF can be controlled by combining the
OUTPUT or OUTPUT NOT instruction with Timer instructions. Refer to Ex-
amples under
5-11-1 Timer – TIM
for details.
4-3-5
The END Instruction
The last instruction required to complete a simple program is the END in-
struction. When the CPU scans the program, it executes all instruction up to
the first END instruction before returning to the beginning of the program and
beginning execution again. Although an END instruction can be placed at any
point in a program, which is sometimes done when debugging, no instruc-
tions past the first END instruction will be executed until it is removed. The
number following the END instruction in the mnemonic code is its function
code, which is used when inputted most instruction into the PC. These are
described later. The END instruction requires no operands and no conditions
can be placed on the same instruction line with it.
Instruction
00000
00001
END(01)
Program execution
ends here.
Address
Instruction
Operands
00500
LD
00000
00501
AND NOT
00001
00502
Instruction
00503
END(01)
---
If there is no END instruction anywhere in the program, the program will not
be executed at all.
Basic Ladder Diagrams
Section 4-3
